Evolution of subjective visual vertical perturbation after stroke

Objective. The perception of visual verticality is often perturbed after stroke and might be an underlying component of imbalance. The aim of this study was to describe the evolution of visual vertical (VV) perturbation and to investigate the factors affecting it. Methods. Thirty patients with herniplegia after a single hemispheric stroke (17 left lesioned [LL] and 13 right lesioned [RL]) were studied. Visual verticality was tested within 45 days of stroke, and then at 3 and 6 months. Subjects sat in a dark room and adjusted a luminous rod to the vertical position. The differences between patients' adjustments and vertical were calculated. The effects on VV evolution of the side, size, type, and location of the lesion were tested. Results. Sixty percent of the recent stroke patients had an initial inaccurate perception of verticality and 39% of these patients recovered during the 1st 3 months after stroke. The evolution of VV tilt depended on the side of the lesion (P = 0.01), with better recovery in LL patients. None of the other factors studied affected VV normalization. Conclusions. The poorer recovery of vertical perception after right-side stroke might be due to the predominant role of the right hemisphere in spatial cognition, and might be involved in the poorer recovery of balance after stroke in RL patients.